Sustaining rotor construction for aircraft



Feb. 14, 1933. J DE LA CIERVA 1,897,042

SUSTAINING' ROTOR CONSTRUCTION FOR AIRCRAFT Filed Dec. 1950 I 2Sheets-Sheet l A TTORNEYS.

Feb. 14, 1933. J D LA c v 1,897,042 I SUSTAINING ROTOR CONSTRUCTION FORAIRCRAFT Filed Dec. 4, 1930 2 Sheets-Sheet 2 INVENTOR. y a de ATTORNEYS.I

V cally disposed axis.

Patented Feb. i4, .1933

UNITED STATES JUAN DE LA crnnvn, or MADRID, seam, ASSIGNOR 'ro AUTOGiROcomm or PATENT .orFlcE.

AMERICA, 01? PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF DELAWARESUSTAINING RQTOR CONSTRUCTIQN F013, AIRCRAFT Application filed December4, 1930. Serial No, 500,062.

This invention relates to sustaining rotor constructions for aircraft,and is particularly concerned with the general type of rotorconstruction which includes a plurality or set of sustaining blades orwings mounted for rotation about a common substantially verti- Theinvention, furthermore, is especially useful in connection with rotorconstructions of this character which are adapted to be actuated byrelative air-flow such for example, as results from movement of thecraft through the atmosphere.

The general nature, obj'ects and advantages of this invention can bestbe understood from a consideration of some of the characteristics ofrotor constructions of the type in question.

The sustaining blades or wings of the type here involved are preferablymounted or arranged in such manner as to provide for relative blademovements both within and transversely of the general path of rotativetravel of the set. To this end, blades of this character are preferablyindividually articulated or pivotally mounted with respect to a commonhub member, so that the blades are free to assume various positions,independently of each other, under the influence of centrifugal,

lift, drag, anti-drag and other forces to which they are subjectedduring rotation and flight operation. i a

it has been found to be desirable to control, limit or yieldingly resistat least certain blade movements or displacements of the characterhereinbefore referred to, and to this end blade interconnections arepreferably employed, an

example of one type of blade interconnection being disclosed inmy-copending application, Serial No. 145,655, filed November 1st, 1926.In addition, resilient means, whichglre operable as to the severalblades independently of each other, are also preferably provided inorder to eifect still further control in a manner fully set forthherebelow.

In many instances when rotor constructions of this type are operating atflight speed, the; resistive forces of the blade interconnections neednot be very great and, indeed, might even be dispensed with oreliminated under some circumstances. This is probably due, at least inpart, to the. greatly increased effect of in- ,ertia forces on theblades themselves when they are operated at flight speeds, so that theblades tend to retain, more closely, their normal (substantially radial)positions.

1 At slow speeds of rotation andparticularly in starting or initiatingrotation of the blade system prior to takeofi, it is highly desirablethat, at least, the larger blade movements should be materiallyrestricted or controlled. However, since the effect of inertia forces onthe blades in starting and at slow speeds is.

furthermore, is advantageous when used in' combination either with amechanical starting device such, for example, as illustrated in myissued Patent No. 1,692,082, dated November 20th, 1928, in which torqueis applied to the hub of the blade system, or with an airflow orslip-stream starter such as disclosed in my copending application,Serial No. 423,773, filed March 3rd, 1930, in which rotation isinitiated by the effect of a current of air moving across the bladesthemselves.

In addition to the foregoing, the present invention contemplates the useof a form of mechanism or apparatus which is not only simple and rugged,but also highly efficient from the standpoint of structure andaerodynamics. e

Other objects and advantages will appear herebelow.

How the apparatus of the present invention may be applied to sustainingrotor constructions, is illustrated in the accompanying drawings inwhich- 1 Figure 1 is a top plan view of a rotor construction of thegeneral character here in-' Figure 2 is an enlarged fragmentary topview, partly in section and partly in elevat1on, of the hub end portionof oneof the blades with various blade pivot parts'associated therewith;and Figure 3 is a view similar to Figure 1 but illustrating a modifiedstructure.

In both Figures 1 and 3 the reference char;

acter 3 designates a central blade mounting or hub member which, it willbe understood, is arranged or mounted for free rotation with the bladesunder the influence of relative airflow. In each one of these figures,furthermore, the sustaining blades are indicated by the referencenumeral 4, each one of the blades being provided with a shank portion 5which is secured or attached to the structure 3 preferably by means of aplurality of pivot or articulated joints, the parts being arranged insuch manner as to provide for individual ivotal movement of the bladeson two diferent axes which are disposedat right angles to each other asindicated in the main views (Figures 1 and 3) at 6 and 7.

From the inspection of Figure 2 it will be seen that the hub or innerend 5a of each blade is provided with the joint part including spacedand apertured lugs 6a. The pivot pin 6 serves to' connect the part 6awith another joint part 7a which, of course, is suitably apertured toreceive the pin 6. The

' joint part 7a, furthermore, is also provided with spaced and aperturedlugs through which the pin 7 extends and between which the block 3a ofthe hub structure is positioned.

' Additionally, a rubber block such as indicated at 5bis positioned ordisposed between relatively moving surfaces of the joint parts 6a and 7a preferably, in such manner as to remain under compression in allrelative positions of the said parts 6a and 7 a. It might. also be notedthat in Figure 2 the full line showing of the blade stub 5a indicates acon siderably flexed position, while the .dot and dash showing at 50illustrates the position which the blade will occupy with respect to thejoint part 7a when the former is in its normal or substantially radialposition.

The structure just described, i. e., the parts employed in the pivotalmounting of the blades with respect to the common hub, is not a part ofthe present invention per se but is described, illustrated and claimedin-my copendin application, Serial No. 496,872, filed Novem er 20th,'1930.'

" Referring now particularly to Figure 1 it will be seen that, inaccordance with the present invention, blade interconnections in theform of cables or wires 9 are provided between adjacent blades, and eachcable 9 is suitably secured atone end to a blade at a ointsuch asindicated at 10, the said point ing spaced substantially from the hubmemblade which carries a-suitable roller 11, the

cable being passed over this roller and extending internally of theblade as indicated at 911. This cable section 9a ispreferably extendedwithin the shank portion 5 of the blade and is secured therein to anadditional cable 12 by means of a connecting or coupling device 13. Thecable 12 in turn is attached to one end of a resilient mechanism such asthe spring 14, the other end of such spring being fixedly mountedpreferably toward the inner end of the blade shank as at 15. 'A weight16, furthermore, is disposed within the blade and arranged for slidingmovement Within a suitable guide such as the tube 17. This weight iscoupled or connected to the device 13, and thus to the cable sections 9aand 12,

by means of a shaft, cable or the like, shown at 18.

According to the application of this mechanism illustratedin Figure 3, awire or cable 19 is attached as at 20 to one blade 4 externally thereof,from which point the cable 19 extends to an adjacent blade carrying aroller 21 over which the cable passes to provide a section thereof, 19aextending substantially lengthwise of the blade shank 5. In thisinstance, however, the weight 22 is interposed between the cable 19 andthe spring device 23 and, if desired, the cable section 19a may beextended directly to the outer end of such spring, in which case theweight 22 may be secured to or mounted thereon. This arrangement isclearly illustrated in Figure 3, and from this figure it will also beseen that these parts are all disposed externally of the blade structureso that they may readily be attached to very simple or small bladestructures. Additionally, the weight 22 is preferably provided withsuitable guide means such as the tube 24 mounted externally of the bladeshank 5 as by means of clamps or brackets 25. The inner end of thespring 23, of course, is secured to a stationarily mounted or fixed partsuch as the bracket or plate 26.

The operation of both forms of the invention above described, generally,is quite similar and includes briefly a very substantialrestraint orrestriction of individual blade movements during initiation of theircommon rotative movement which may be effected, for example, by means ofeither a mechanical or slip-stream type of starter mechanism such asthose hereinbefore referred to. This substantial restriction or controlresults from the combined effect of the blade interconnections abovedescribed and of the resilient block or device 5?) which, is associatedsustaining system is inactive or at rest. However, as brou ht outclearlyin my copendin application, S eria-l No. 496,872 above referreto, resilient stops of this character are referably so designed as topermit the bla es to move freely or, at least, without any substantialrestraint during normal flight-rotation, it being noted that it ishighly desirable that the blades should be free, independently, toassume various positions of equilibrium under the influence ofcentrifugal, lift, drag and anti-drag forces. This relative freedom inflight, also as brought out in the last mentioned coending application,is due to the fact that t e restrictive force exerted by the" rubberblocks or cushions is not sufficient to materially hamper or impairmovements which are caused by the normal flight forces such asthose justreferred to.

The resistive value of the blade interconnections disclosed herein, inthe preferable arrangement, is so proportioned with respect to that ofthe resilient cushions associated with the blade pivots and the effectof centrifugal force on the blades themselves, that,

just after initiation of rotation and during the l ver rotationalspeeds, the blade interconnections serve to exert a substantialresisting force as to the movements of one blade with respect to anotherin their general path of travel. In this connection, it should be bornein mind that shortly after initiation of rotation, the action ofcentrifugal, drag and anti-drag forces is such as to materially reducethe efiect of the resilient stops or cushions at the blade hubs so thatat such times, and before flight speed of rotation is attained, theblade interconnections serve-to substantially prevent any undesirablygreat individual blade movements under the influence of the startingforce which is being applied to the system. However, as flight speeds ofrotation are approached, the weight devices 16 or 22 which areassociated with the blade interconnections are affected sufficiently bycentrifugal force to materially reduce, if not completely eliminate, theeffect of the blade interconnections, it being noted that at flightspeeds of rotation theaction of inertia forces on the blades is, in manyinstances, suflicient to maintain the desired blade positions. I prefer,therefore, to relatively arrange and proportion the resistive value ofthe blade interconnections and the weight devices in suchmanner as tosubstantially eliminate the effect of the blade interconnections atflight speeds of rotation.

It will be seen, therefore, that the size or mass as well as thedisposition of the weights 1 6 and 22 may be arranged, relativelyto various forces acting on the blades, either to completely eliminate theaction of a blade interforce on the'outer portions of the blades atflight'speeds of rotation, the weight devices may he so proportioned andarranged with respect to mass and extent of. movement under theinfluence of centrifugal force as to suitably alter the center ofgravity of the blade lengthwise thereof and thus provide for automaticshift of the center of gravity of the blade outwardly as flight speedsof rotation are approached.

According to the foregoing, therefore, the present invention makesprovision for relatively great restriction or control of individualblade movements in their general path of travel at starting and at thesame time provision for relatively great, or, if desired, complete,freedom for such movements during normal flight operation. In addition,the present invention accomplishes the above as well as other objectsand advantages hereinbelow pointed out, by the use of a simple,convenient and effective form of apparatus.

In connection with the application of the structure illustrated inFigure 1, it should be noted that, in this instance, all of theoperating or movable parts of the interbracing system, with theexception of a single section may be desirable for certain installationsfor I this reason. In addition, the simplicity of the constructionillustrated in Figure 3 greatly facilitates application thereofexternally of the blade and, therefore, in some cases, especially wherethe blade structure itself does not readily lend itself to the internalapplication, this particular arrangement is very desirable. It will beunderstood, of course, that with this last type of application, theparts which are located externallyof the blades may be suitably fairedor stream-lined with the s ank portions of the blades.

I claim: 1

1. In an aircraft, a set of sustaining blades mounted for rotation-abouta common axis With freedom for movement of one blade with respect toanother, and a mechanism for controlling said movement, together withmeans associated with said mechanism and influenced by the action ofcentrifugal force dur ing rotation of the set of blades to progressively decrease the controlling effect as the speed of rotationincreases.

2. Inan aircraft, a set of sustaining blades mounted for rotation abouta common axis with freedom for movement of one blade with 1 v, v P

respect to another, and a mechanism for controlling said movement,together with means associated with said mechanism and influ- 'enced bythe action of centrifugal force during rotation of the set of blades toprogressively decrease the controlling efi'ect substantially to the zeropoint at normal flight speeds of rotation.

3. In an aircraft, a set of sustaining blades mounted for rotation abouta common axis with freedom for movement of'one blade with respect toanother, and a mechanism for controlling said movement, including meansyieldingly resisting said movement and means operative by the action ofcentrifugalfor controlling said movement, including bladeinterconnections yieldingly resisting said movement and a deviceassociated with the blade interconnections and influenced bythe actionof the centrifugal force during rotation of the set of blades toprogressively decrease the controlling efiect as the speed of rotationincreases. V

5. In an aircraft, a set of sustaining blades mounted for rotation abouta common axis with freedom for movement of one blade with respect toanother, and a mechanism for controlling said movement, together withmeans associated with said mechanism and influenced by the action of thecentrifugal force during rotation of the set of blades to decrease thecontrolling effect as the speed of rotation increases.

6. In an aircraft, a set of sustaining blades mounted for rotation abouta common axis with freedom for movement of one blade with respect toanother, and a mechanism for controlling said movement, including bladeinterconnections yieldingly resisting said movement and a deviceassociated with a blade interconnection and influenced by the action ofcentrifugal force during rotation of the set of blades to decrease thecontrolling effect as the speed of rotation increases.

V 7. An aerial device having a set ofsustaining blades mounted forrotation about a common axis with freedom for movement of one blade withrespect to another in addition to the common rotation of the set andmeans for controlling relative blade movement including a resilientdevice associated with a plurality of blades and weight means associatedwith the resilient device and arranged for movement, under the influenceof centrifugal force during the said common rotation of the set ofblades, to control the effective resilience of said device.

8. An aircraft having a set of movable sustaining blades, a blademountin structure providing for rotation of the set a out a common axisand relative movement thereof in addition to the common rotation and amechanism for controlling relative blade movements including tensionblade interconnecting means and a weight arranged formovement under theinfluence of centrifugal force and associated with said interconnectingmeans in such manner as to control the tension thereof. 1 Y

9. An aircraft having a set of movable sustainin blades, a blade mountinstructure provi ing for rotation of the set about a common axis andrelative movement thereof in addition to the common rotation and amechanism for controlling relative blade movements including tensionblade-interconnecting means and. a' weight arranged for movement underthe influence of centrifugal force and associated with saidinterconnectingoneans in such manner as to control the tension thereof,said weight being carried by a blade.

10. An aircraft having a set of movable sustaining blades, a. blademounting structure providing for rotation of theset about a common axisand relative movement thereof in addition to the common rotation and amechanism for controlling relative blade movements including tensionblade-inter connecting means and a weight arranged for movement underthe influence of centrifugal force and associated with saidinterconnecting means in such manner as to control the tension thereof,said weight being mounted within a blade. I

11. An aircraft having a set of movable sustaining blades, a blademounting' structure providing for rotation of the set about a commonaxis and relative movement thereof in addition to the common rotationand a mechanism for controlling relative blade movements including bladeinterconnecting means, a device adapted to place the interconnectingmeans under tension and a weight arranged for movement under theinfluence of centrifugal force and associated with said device insuchmanner as to control the tension thereof. a

4 12. An aircraft having a set of .movable sustaining blades, a blademounting structure providing for rotation of the set about a common axisand relative movement thereof in addition to the common rotation and amechanism for controlling relative ,blade taining blades, a mountingstructure for said blades including means providing for rotation of theset about a common axis and means providing for pivotal movement of oneblade with respect to another, means astrolling movements of the blade,and means acting progressively as rotational speed 1ncreases, todecrease the effect of the control means.

19. In an aircraft, a set of sustaining blades mounted for rotationabout a common axis with freedom for movement of one blade with respectto another, and a mechanism for controlling said movement, together withmeans associated with said mechanism and influenced by the action ofcentrifugal force during rotation of the set of blades to decrease thecontrolling efiect substantiall to the zero point at normal flightspeeds o rotation.

In testimony whereof, I have hereunto signed my name. JUAN'DE LACIlflRVA.

sociated with the pivot means'for controlling pivotal movements and 'adevice associated with a plurality of blades for controlling suchpivotal movements, said device including means operable under theinfluence of the centrifugal force incident to the common rotation ofthe set of blades to reduce the controlling efiectbf the device asthespeed of rotation increases.

15. An aerial device having a set of sustaining blades, a mountingstructure for said blades including means providing for rotation oftheset about a common axis and means providing for pivotal movement orone blade with respect to another, means associated with the pivot meansfor controlling pivotal movements and a device associated with aplurality ofblades for yieldingly resistinf such pivotal movements, saiddevice inclu ing means operable under the influence of the centrifu alforce incident to the com mon rotation o the set of blades to vary the 7effective resistive value of the device.

16. An aerial device including a set of movable sustaining blades, ablade mounting structure providing for rotation of the set about acommon axis and relative movement thereof in addition to thecommonrotation v and means associated with a blade and operable under theinfluence of changes in' the effect of centrifugal force at differentspeedsof rotation to alter theposition of the center of gravity of theblade.

17 In an aircraft a sustaining rotor with a blade mounted thereon,having means permittixng blade displacement movements under the iuen'ces of various forces, means controlling movements of theblade, andweight means mounted in association with said blade for movementgenerally along its axis under the influence of variations incentrifugal force to alter the effect of the control means. 18. In'anaircraft, a sustaining rotor with a blade mounted thereon, having meanspermitting blade displacement movements under the influences of variousforces, means con-

